[TheForge] Fwd: Shop tools & layount (3-phase converter)

Sun Jan 18 11:30:24 2004

You only consume power when the motors are doing work. The idler motor 
(the extra motor you refer to) improves the power supplied to the work 
motor, but doesn't do any work (it does have parasitic losses due to the 
windings not being perfect conductors). The idler is essentially acting 
like a transformer, providing the third leg with little or no loss.

I've seen measurements made on a rotary converter setup that showed the 
rotary setup, including both idler and work motors, consumed less power 
(a little less) than a single phase motor running at the same load. Not 
true when there is no load and the idler is spinning, of course.

The other aspect of affordability is what the motors cost. If you have 
to buy motors new, by all means use single phase. On the other hand, 
three phase motors are often available pretty cheap if you're a good 
scrounge, while single phase motors aren't.

Steve Smith

RL Crawford wrote:
> For a phase converter, don't you need the same size or larger motor than the
> one you're trying to run in the first place?  Seems to me that the power
> used would overcome the initial savings on the motor.
> 
> Please tell me what I am thinking wrong.
> 
> Thanks,
> Rick Crawford at Rafter Lazy C
> Home of Smoky Forge and Lem the Wonder Mule
> in the middle of Northern Illinois
> email = [email protected]
> http://www.SmokyForge.com
> http://www.RafterLazyC.com
> 
> and remember -
> Even if you're on the nright track,
> you'll get run over if you just sit there.
>                       Will Rogers
> 
> ----- Original Message ----- 
> From: "Steve Smith" <[email protected]>
> To: <[email protected]>
> Sent: Saturday, January 17, 2004 8:45 AM
> Subject: Re: [TheForge] Fwd: Shop tools & layount (3-phase converter)
> 
> 
> 
>>
>>Kenny O. wrote:
>>
>>
>>> is there a way to change a three phase motor to be used with 220 ...
>>> I see them much cheaper at the tool zoo?  I also saw this thing
>>> called a phase-a-matic which cost $150.00 .  Its claim is to be a
>>> "static phase converter".  Has any one used these things or
>>> attempted to make there own?
>>> Thanks
>>> Kenny o
>>>
>>
>>This works really well Kenny. If you're a good scrounge and have enough
>>experience to be comfortable and safe wiring up 220VAC equipment, you
>>can build your own fairly cheaply. 3 phase motors (and equipment) often
>>go for much lower prices at auctions and other used sales because no one
>>can plug them in (except those who have a phase converter at home).
>>
>>There are two things you need to run a 3 phase motor on single phase
>>220, a way to start it and a way to get the HP you need out of it.
>>Static phase converters only give you a way to start. Read some and see
>>if you're comfortable with building this kind of stuff, and ask us
>>questions.
>>
>>Steve Smith
>>
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